The present invention relates to the technical field of internal combustion engines, and more particularly engines with ignition controlled by means of sparkplugs.
The invention relates more particularly to an ignition unit comprising, for each sparkplug of the engine, an electrical coil suitable for taking electrical energy from a low voltage source and for supplying the associated sparkplug with energy at the high voltage required for producing an ignition spark inside a combustion chamber titted with such a sparkplug.
Although the ignition systems of such engines initially comprised a single ignition coil with high tension electricity then being distributed from it to each of the sparkplugs via a mechanical or electronic distributor, proposals are known whereby each sparkplug is fitted with an individual ignition coil. The intended purpose of such a proposal is to reduce the lengths of the conductors or cables carrying high voltage energy, thus making it possible to limit the major electrical leaks that impede proper operation of the engine and that also degrade the radio environment of such engine.
It should be assumed that such a xe2x80x9cmonostaticxe2x80x9d ignition unit, i.e. a unit requiring one coil to be implemented for each sparkplug of an engine, possesses the major drawback of presenting large bulk compared with an ignition unit comprising a coil that feeds a plurality of sparkplugs. Unfortunately, the amount of room available around an engine is always restricted.
Furthermore, it should be observed that because it implements a plurality of coils, a monostaic ignition unit requires numerous electrical connections between each coil, specifically its primary and secondary windings, and secondly the controlling and monitoring electronics that is associated with such coils. Such electrical connections lead quite naturally to an increase in the general bulk and the manufacturing costs of such a unit.
The object of the invention is thus to seek to remedy the drawbacks specified above by proposing an ignition unit for at least two sparkplugs of an internal combustion engine, the unit being designed to present little bulk and low manufacturing cost.
Another object of the invention is to propose an ignition unit designed to enable the electrical connections between the various components of such an ignition unit to be implemented in simple manner and at low cost.
To achieve such an object, the ignition unit for at least two sparkplugs of an internal combustion engine is constituted in the form of a box comprising internally:
a reception cavity for receiving an electronic printed circuit;
a series of mutually separate housings extending side by side transversely relative to the reception cavity; and
a series of ignition coils each fitted with a primary connector comprising firstly a fixing member for fixing the ignition coil to the box to enablle said ignition coil to be mounted in a corresponding housing, and secondly connection terminals between the ignition coil and the printed circuit.
The above described ignition unit is particularly suitable for enabling the box constituting such an ignition unit to be subdivided into two sealed portions, specifically one portion for the coils and a second portion for receiving the controlling electronics. To achieve such an object, the unit comprises:
a separating partition between the reception cavity and the housings, the separating partition leaving a through opening between each housing and the reception cavity;
as the fixing member for each primary connector, a separator panel having connection terminals passing through it, the panel being for mounting in the operating partition to close the corresponding through opening;
an electrically insulating potting compound of a first type filling the reception cavity for the printed circuit; and
an electrically insulating potting compound of a second type filling the housings.